In a vertical mixing device as known from practice two vertical augers are provided the distributor cones of which are almost symmetrical because their upper tips are located vertically above the centers of their bases.
NL 10 06 275 A discloses a vertical mixing device comprising two vertical augers which can be driven with opposite senses of rotation. The vertical mixing device can be filled from the rear side. Both augers rotate with different speeds and are provided with an overlap between their rotation courses. They carry controlled conveying elements. Both distributor cones are symmetrical. The upper tip of each distributor cone is situated essentially vertical above the center of the bases.
In a vertical mixing device as known from U.S. Pat. No. 5,240,321 A, four vertical augers in total are provided in a series in the longitudinal direction of the mixing chamber. There are partial overlaps between the mutual rotational courses of the augers. Said mixing chamber can be filled from one end. The mixed fodder is expelled at the other end. During a mixing procedure the vertical mixing device is elevated at one of its ends.
It is conventional to fill the vertical mixing device either from the upper side by exterior means or to fill it with fodder by means of its own filling device situated at the rear end. In case that the mixing chamber is filled from above by exterior means, particularly between said vertical augers, first the fodder is distributed on both vertical augers. Each vertical auger forms a mound like a mole hill by its upward conveying effect during the mixing procedure. The distributor cones provided should prevent dead spaces in which the fodder is accumulated without motion and also should promote a transfer of the fodder from one vertical auger to the next one. Said distributor cones are for guiding the fodder from above, downwardly and inwardly to the auger lobes. However, the fodder also should move back and forth between both vertical augers in order to avoid irregular feed mixes. If the mixing chamber is filled from its rear end it is even more complicated with several vertical augers provided to distribute the latest loaded fodder part regularly within the mixing chamber. A regular mixture of the fodder hardly can be achieved by the known measures or only after an extremely long mixing duration.
A distributor cone as mentioned here is to be seen as a structure similar to one half of a four sided pyramid separated in a vertical diagonal plane. Said half pyramid is set with its partition plane to the longitudinal wall of the mixing chamber. The base sides and the outer surfaces of said pyramid can be concavely curved in the upward direction and/or in the horizontal direction. The concave curvature in horizontal direction can be made continuously or can consist of discrete straight sections. The upper tip of the distributor cone can be a true pointed tip or can be designed like a rounded peak.
It is an object of the invention to create a vertical mixing device of the kind as disclosed by which irrespective of the manner of filling the mixing chamber an intensive, regular mixture is achieved after relatively short mixing duration.
By means of the oblique inclination of a distributor cone towards the vertical auger, the sense of rotation of which is directed towards said distributor cone, a significant part of the fodder is conveyed upwardly along the steeper guiding surface of the distributor cone. Said fodder part is then guided over the tip and over the edge extending towards the tip of the distributor cone to another guiding surface of the distributor cone and from there to the other vertical auger where it is taken up by said other vertical auger. In a top view of a well filled mixing chamber a continuous and quick oval circulation of the fodder can be seen which means that from each mound of one vertical auger a significant part of the fodder moves over to the other vertical auger. As a result, essentially identical feed mixes are achieved at each vertical auger as well as an intensified regular fodder mixing effect within the entire mixing chamber. This is achieved after a relatively short mixing duration. Contrary to a distributor cone, the tip of which is situated almost vertically above the center of the base and the guiding surfaces of which are symmetric, the steeper side surface of the distributor cone according to the invention generates unexpectedly strong rising tendencies for the fodder in co-action with the circumferential and upward conveying force components of the vertical auger feeding towards said distributor cone said force component guides considerable fodder parts quickly from one vertical auger over the distributor cone to the other vertical auger. Said vertical augers may be aligned in the longitudinal direction of the mixing chambers, or laterally or even obliquely. In each case it is expedient to provide distributor cones within the intermediate wedge areas of the vertical augers.
The inclination of the distributor cone structurally is achieved by displacing the upper tip, e.g. alongside the wall towards which the respective vertical auger is feeding. By said displacement the guiding surfaces of the cone have mutually different inclinations towards the tip. In relation to the vertical plane the distributor cone is made significantly asymmetrical. At the steeper guiding surface the fodder parts arriving from the vertical auger feeding towards said steeper guiding surface climb upwardly until they change over the tip and the upwardly directed edge to the other less steep guiding surface along which they slide downwardly and inwardly to the other vertical auger which then conveys the fodder further.
Expediently the tip of the distributor cone is offset by an extent leading to a geometrical relation according to which the boundary between the distributor cone and the longitudinal wall at the side remote from the auger feeding towards the distributor cone is essentially parallel to a line representing the upward taper of the vertical auger, when looking perpendicularly onto the longitudinal wall of the mixing chamber.
The guiding surfaces can be formed straight or can extend with a concave curvature in upward direction to the tip.
Furthermore, in a horizontal section of the distributor cone, the guiding surfaces may be curved concavely. Said curvature can be a uniform curvature or can consist of several straight section.
From the pointed end of the cone base extending into the wedge between the vertical augers an edge extends obliquely upwardly towards the sidewardly offset tip. Said edge defines a borderline of the less steep descending guiding surface towards the auger conveying the fodder away. The fodder which already changed over onto said less steep guiding surface slides down rapidly towards said vertical auger.
The pointed ends of both wedge areas expediently are located on a centre line extending laterally between the respective two vertical augers.
The wall, e.g. a longitudinal wall, at which the distributor cone is located may extend vertically or may be inclined outwardly, depending on the design of the vertical mixing device. The tip may be situated directly at the wall or can be distant from the wall and connected to it by a spacer or the like.
For easy manufacturing each distributor cone should be a construction of welded sheet metal which is prefabricated and secured e.g. to the longitudinal wall.
The tips of the distributor cones provided should be situated above the level of the free upper ends of both vertical augers in order to promote a lively circulation in case of a well filled mixing chamber. The inclined distributor cones are of advantage irrespective of whether the mixing chamber is to be filled from one end or by means of exterior means from the upper side and between both vertical augers.
In case of a large volume of the mixing chamber even more than two vertical augers may be provided one behind the other. Between respective two vertical augers the oppositely inclined distributor cones are provided. In this way even in a longer mixing chamber a lively oval circulation of the fodder is generated alongside the side walls and also at the expediently rounded terminal walls. It is to be noted that additionally a transfer of fodder also takes place directly between the vertical augers. Said fodder transfer contributes to the regularity of the feed mix.